Do you live near a major road? A power plant? In a dense neighborhood, or in a suburb? Close to a supermarket with lots of fresh fruits and vegetables?

Factors such as these, said Francine Laden, Mark and Catherine Winkler associate professor of environmental epidemiology, can have an impact on your health.

Laden spoke about environmental epidemiology research in general as well as her own research, on how where you live in the United States can affect your health, at a July 26, 2011 talk that was part of the School’s summer Hot Topics lecture series.

While there are a variety of instruments that can monitor potential environmental health threats from things like secondhand smoke, air pollution, UV light, or electromagnetic fields, Laden noted that these instruments tend to be expensive, making it difficult to measure large populations. More often, she said, researchers study environmental health effects by examining data from longitudinal studies that track people over time.

Laden’s research group has examined data from the Nurses’ Health Study, the Harvard Six Cities Study, and the Trucking Industry Particle Study. Through such studies, environmental epidemiology researchers ask key questions that help pinpoint potential causes of disease, such as: Are you exposed to dust and fumes in your job? Do you spend time in smoky bars? Do you drink tap water?

Laden’s research group has found a number of links between environmental factors and health. For example, the results of one study showed that greater exposures to UV light correlate with a higher incidence of squamous cell carcinoma. In some regions of the U.S.—for example, the Southwest—people are more exposed to UV light and thus face a higher risk.

Other research from Laden’s group has shown an association between fine particulate levels in the air and mortality rates—the more fine particles, the higher the rate. The researchers found relationships between particulates and increased levels of cancer, renal failure, coronary heart disease and cognitive decline. They also observed associations of some negative health outcomes—for instance, rheumatoid arthritis and diabetes—among people living closer to highly traveled roads. In regions of the U.S. where air pollution has decreased over time, Laden said, there has been an improvement in public health.

Sometimes the environment in which a person lives can have a positive effect, she noted. For instance, research from her group has shown that women living in densely populated areas get a protective effect against obesity—likely because they walk more and drive less than their suburban counterparts.